Method and means for the reproduction of intelligence



sep1.l24, 1946.

N. H. YOUNG, JR

METHOD AND MEANS FOR THE REPRODUCTION OF INTELLIGENCE Filed Feb. 20,'1943 AT' my Patented Sept. 24, 1946 f Q v,2,408,117

AN D- MEANS FR'TI-JI REPRODUC- TION'OFfINTELLIGENCEv METHOD Norman H.Young. .Ir.,-JackscnHeights, N. Y.,v as- I signor to kFederal YTelephoneand Radio Corporation, Newark, N. J., a corporation of Dela- YApplication February 20, 1943,.- SerialNo.Y 476,604

This invention relates. tomethod and means for the` reproducti'on ofintelligence; and more par.- ticularly'to a communicating system whichis vdifcuit of interference by jamming; 1

An object of this invention is'the provision'o'f a novel; system for thereproduction of intelligencefrom transmitted and received signals.

Another object' is to provideV such a system which is difficult tojam.4

' A further, morespecific object of this` invention is tovprovide a'communicating 'system wherein' the successful reproductionofintelligence depends upon vthev repetition cfaV signal ata constant,variable, or'continuallyvarying predeter=' minedv interval. y i

Other objects and advantages of the present inventionvvill:becomeapparent fromn the following'description of a preferredfembodiment,together with afm'odication thereoillustrated in the accompanyingdrawing, in which: Fig. lis a block circuit diagram of a communicatingsystem in accordance with the present invention, schematically showingcertain novel fea-tures thereof; Y

Fig. 2 diagrammatically shows examples of received intelligence; j

Fig.3 diagrammaticalfly shows examplesof signalscorresponding totheexamples of'reproduced` intelligence shoWninFig. 2;

Fig. .4 illustrates a modification of; theN apparatus illustrated inFig. 1.

The system of the present invention isf particularlydirected to thereproduction'oi intelligence in the form of letters or correspondingkindicia upon the screen of a cathode ray tube. The mechanics of suchreproduction are in themselves well-known and the inventionvcontemplates using present methods in the step of reproduction per se.However, the method of transferring the received signals to theintelligence reproducer provides, in accordance with the presentinvention, a new system which, as will becomey apparent as thedescription proceeds, provides an arrange ment which is extremelydiflicult to jam.

AS illustrated in Fig. 1, my system utilizes a receiver l fordemodulating the received signals. The receiver Ill thus acts as asignal source, the output of which is applied simultaneously to aInagnetizingv coil I2 and a normally blocked amplifier I d. Themagnetizing coil I2 is placed in juxtaposition to a magnetizable Wheel I6 driven at constant speed by any suitable means such as motor I8. Thereceived signals operating through the coil I2 will, accordingly,magnetize the rim of this Wheel IB in accordance with such" signals,

10y claims. (c1. 17e-7.3)

. 2l and'in a ,mannerV which is. per se Well-known in the art. Themagnetization of the Wheel I6' will, upon rotation of. the latterand-,after a predeterminedtime interval be picked up` and reconvertedinto signaisby the pick-up coil 2U. This is connectedjthrough a suitablerectifier 2.2 to produce, foreach signal component, an unblockingpotentialiappli'edto the normally blocked amplifier lli.

A suitable reproducer 24,` which may be a cathode ray tube is fed fromthe block amplifier I.

- After the signals have loteeifipickedV up by the coil 26, themagnetization vof the wheel producing such isignals is erased-bysuitablemagnet 26.

i It vvillbe clear from'the foregoing description of the illustratedvapparatus that when va signal is'derived from thereceiver lll it will beimpressed upon the magnetizable Wheel 'through the coil !2,. but cannotpass through the reproducer 2f?. since vthe amplifier Ill`isnormally'blocked. However, ifV this-signal is repeated at an intervalsuch that the amplifier `Avvill be unblocked by the first signal at thesame time. that the second signal is received, this. second signalwillpass through the amplifier to the reproducer. It is accordinglycontemplated-by the present system that each signallt'o be reproduced asintelligence must vbe repeateoiat a time interval which will be theequivalentoi the: time which it takes' for the Wheel I6 to move frombeneath the coil i2 to beneath' the -coil 2B. Accordingly, unless thejamming signals are' timed synchronously with theV interval* betweenduplicated signals the jamming effect thereof will be lost. Thus,essentially, in the form of invention illustrated in Fig. l, I haveprovided a system vvhichY can only be jammed if thejammingsignals are insynchronism with the duplication of Ysignals to be jammed. They mannerin which the foregoing system works may be made clearer in connectionwithy thatif itisdesired to reproduce the letter "l',k

Fig. 2'Y (A), the signal producing' this letter will have. somewhat theform as illustrated in Fig. 3

(A)- When the first series of pulses such as Y shown in Fig. 3' (A)c'omethrough the receiver I0 theyV will not passthe blocked amplifier idbut will be impressed. upon themagnetizable wheel IB. When themagnetized impressionupon fthe vvhe'elllv pass beneath the pick-up 2),Ythe duplication `oftheoriginal signal, Fig. 3 (A) will come `through thereceiver III, but at this time the sig,-

, nalwilli .pass throughi the amplifier .i4 since the LE amplifier willbe synchronously unblocked by the pick-up 20 and the rectier 22 by anunblocking potential which will be of a duration corresponding to theindividual signal components simultaneously applied from the pick-updevice 20. Thus, the second signal coming from the receiver IB will beused to produce a letter while the rst signal at a later time is used tounblock the amplifier.

If, now, it is desired to send a second letter such as the letter E,Fig. 2 (C) there may be one period of overlap during which the secondsignal for the letter T will be app-lied to unblock the amplier I4, atthe same time the'rst signal for the letter E is coming from thereceiver. This overlap will produce a signal on the screen of thecathode ray tube such for example as shown in Fig. 2 (B), but it will beimmediately recognized by the operator as having no meaning and will notseriously interfere with the interpretation of the intelligence to beconveyed. This false indication is caused by the unblocking of theamplifier i4 in accordance with the pulses shown in Fig. 3 (A)representing the letter T, and the simultaneous application of thedirectly applied signal shown in Fig. 3 (B) representing the letter ELThe amount of overlap is represented by the short pulses shown in Fig. 3(C).

It will be recognized that the amount of overlap and consequent falsesignal will be greatest when the signals representing the leastsequential letters or indicia follows the prior letter at a timeinterval which is exactly the same as that between the duplicate signalsof each letter.

If however, the spacing between duplicated signals' for each letter issufficiently great no interference whatsoever will be produced, since bythis time the second impression of the prior signal upon themagnetizable wheel will have already passed the pick-up 2l), andprobably the demagnetizing device 26 before the iirst signal for thesecond letter has been received.

While the aforedescribed system is, as previously pointed out, difficultto jam, there is still the possibility that a jamming station mightdiscover the periodicity between duplicated signals for each letter andif the jamming were in Synchronism with the interval such jamming wouldbe effective. It is therefore contemplated that the position of eitherthe coil I2 or the coil 20 be varied, either manually in accordance withsome prearranged signal from the transmitting station, so that the timeinterval would be changed from time to time, or the position of one ofthese coils could be made to vary continuously in some predeterminedmanner which is synchronized in a corresponding change in sendinginterval at the transmitter. In Fig. 4, I have illustrateddiagrammatically one arrangement which permits a continuous controlledshifting of the position of the pick-up coil 20. In this case, themagnet 20 is mounted by any suitable means upon a :block 30 whose motionis constrained about the periphery of the wheel I6 by a suitable lever32 which may be mounted about the shaft of the wheel IB. The block 30 isconnected by a link 3e to a gear 36 by an oiset pivot 38. The gear 36may be driven by a smaller gear 3l) which is connected by a shaft 42with the driving shaft of the wheel I6. Through this arrangement it willbe clear to those Skilled in this art that upon rotation of themagnetizable wheel I6 an oscillatory circular motion will be applied tothe block 30 thus the magnet 20 by the gears 3B and 40 through the'pivot38 and the 4 link 34. It is specifically pointed out however, that themeans for particularly oscillating the magnet 20 such as illustrated inFig. 4 have only been given by way of example and that any one of themany well-known linkages for transferring rotary 'motion in'tooscillatory motionl could be used.

Attention is also directed to the fact that while the reproduction ofintelligence is, in the preferred embodiment illustrated, controlled bythe blocking and unblocking o-f an amplier, this control is, in eiect,an electronic on oil switch between the receiver and reproducer and itis contemplated that other equivalent switching devices eitherelectronic or electromagnetic could be used.

The invention has been particularly described in connection with thereproduction of the rst of two signals upon a'magnetizable wheel to givethe required time -delay between duplicated signais in accordance withthe principles of my invention. It is contemplated, however, that otherequivalent and well-known means might be used in place of a magnetizablewheel. For example, a continuous magnetizable tape could be used in thesame manner as a magnetizable wheel. The principles of the inventionwould, moreover still apply if the first signal were applied toa paperor similar tape either 'by inking the signal therein or forming thesignal by suitably perforating the tape, in which' case thepickup 20would be spaced longitudinally along r`the tape in its direction ofmovement, the typeof pick-up 20 depending upon the type of recordingdevice used. If a paper tape system were used, the paper would probablybe discarded after use and no erasing device would be required. Thesepossible applications of my vinvention make use of well-knownarrangements and since their use is believed to be obvious to thoseskilled in this art, no illustration of these equivalents is deemednecessary.

While the invention appears to be particularly applicable to systems inwhich the signals are reproduced as visual intelligence upon the screenof a cathode ray tube, it is deemed obvious thatI other types ofreproducers known in the art may be used. In all cases, however, theprinciple of requiring a duplication of signal before the same can bereproduced is to be considered as the basic novel feature.

.Accordingly while I have described above the principles of my inventionin connection with certain specific apparatus, and have described oneparticular modication thereof, it is to be clearly understood that suchdescription is made only by way of example and not as a limitation onthe scope of my invention as set forth in the objects andtheaccompanying claims.

I claim:

1. An intelligence reproducing system including, in combination, areceiver, a normally blocked amplier connected to said receiver, anintelligence reproducer connected to said `amplier, movablesignal-recording means, a recorder connected to said means forimpressing received signals thereon, a pick-up device positionedadjacent said means and spaced from said recorder f in the direction ofmovement of said means for reproducing the recorded signal, and mean@`activated by said pick-up device for unblocking said amplifier.

2. The combination according to claim l, in which said signal-recordingmeans is a magnetizable wheel, said recorder is a magnetizing 5` device,and said pick-up is responsive to the magnetization of said wheel. Y

3. The combination according to claim l, in which said signal-recordingmeans is a magnetizable wheel, said recorder is amagnetizing device, andsaid pick-up is responsive to the magnetization of said wheelincombination with' means intermediate said pick-up and said recorder inthe direction of rotation of said wheel for demagnetizing the latter.

4. The combination according to claim 1,'in combination with means *forlongitudinally varying the position of said pick-up relatively to saidsignal-recording means.

5. The combination according to claim 1, in combination with means forperiodically longitudinally varying the position of said pick-uprelatively to said signal-recording means.

6. An intelligence reproducing system comprising a signal sourceincluding signal recording means for repeating the signals, anintelligence reproducer, and control means intermediate said signalsource and said reproducer, said control means including means solelyresponsive to a predetermined periodic duplication of a signal from saidsource for activating said reproducer to reproduce said signal.

7. An intelligence reproducing system including, in combination areceiver, a normally blocked amplifier connected to said receiver, anintelligence reproducer connected to said amplier, means for unblockingsaid amplier for periods corresponding to the duration of individualsignal components, and time delay means including a signal recorder forenergizing said unblocking means a predetermined time after thereception of a signal on said receiver, whereby said amplier is onlyunblocked to pass intelligence to said reproducer whenever the signal isduplicated at Y delay means in accordance with the time interval betweenlduplicated signals.

9. An intelligence reproducing system including in combination, a signalsource including a recorder adapted: to repeat each signal at least onceat a predetermined time interval, means for converting a signal intovisual intelligence, a normally blocked amplifier intermediate saidsignal source and said reproducer, and means responsive tothe rst of apair of identical signals for unblocking said amplier after saidpredetermined time interval, whereby the second of said identicalsignals will be applied to said reproducen 1 10. An intelligencereproducing system, in cluding in combination, a signal source includinga recorder adapted to provide at least one sequential duplication ofeach desired signalat a predetermined time interval, anintelligencereproducer, normally blocked connecting means intermediatesaid signal source and said reproducer, means for unblocking saidconnecting means, and means for activating said unblocking means by therst of each duplicated signal synchronously with the application of thesecond signal to said connecting means, whereby the second of the twosignals is converted into intelligence by said reproducer.

NORMAN H. YOUNG, JR.

